Changing keyboard layouts in Win 8.0

My wife has an Asus Win 8 laptop. It was bought in the US, and we live in the US, but for numbers, dates, spelling etc we use British settings. So during the initial setup I chose British English as the language, but left the keyboard as US since that is what it is. All was well until today when without provocation the @ and " (quotes) switched. (UK keyboard? I'm not sure.) I have tried Control Panel > Keyboard, and various MS on-line help articles, but haven't yet hit upon the right link to sort out the muddle. I'm sure it's simple, but......